Why is rigged car's XYZ location different from its physical XYZ?
It's because your model and/or your Armature hasn't "applied" their scale. It's always a good practice, at the end of the modelling stage, to apply rotation and scale to every object, so that rotation results in 0,0,0 and scale 1,1,1.

To do it, select an object and press Ctrl+A, then choose rotation and scale.

After you correctly applied rot and scale to both mesh and armature, you can establish their armature parentship, and you will have correct measurements.